Title:Current Perspective of COVID-19 on Neurology: A Mechanistic Insight
Volume: 25
Issue: 5
Author(s): Rajesh Kumar, Seetha Harilal, Sabitha M., Leena K. Pappachan, Roshni P.R. and Bijo Mathew*
Affiliation:
- Department of Pharmaceutical Chemistry, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham,
AIMS Health Sciences Campus, Kochi-682 041, India
Keywords:
SARS-CoV-2, Covid-19, neurology, post Covid-19 syndrome, OE, BBB.
Abstract: SARS-CoV-2, the novel coronavirus and the causative organism of the Covid-19
pandemic wreaked havoc worldwide producing asymptomatic to symptomatic cases leading to
significant morbidity and mortality even after infection. Most of the countries reported a mortality
rate of 2-3 % majorly due to cardiorespiratory failures. Recent studies highlighted the neurological
involvement playing a key role in cardiorespiratory failures and other symptoms such as headache,
anosmia, and ageusia observed in Covid-19 patients. Studies suggest SARS-CoV-2 entry via
Olfactory Epithelium (OE), and the expression of type 2 transmembrane serine protease
(TMPRSS2) in addition to Angiotensin-Converting Enzyme 2 (ACE2) can facilitate SARS-CoV-2
neurotropism. The virus can either travel via peripheral blood vessel causing endothelial
dysfunction, triggering coagulation cascade and multiple organ dysfunction or reach the systemic
circulation and take a different route to the Blood-Brain Barrier (BBB), disrupting the BBB
causing neuroinflammation or neuronal excitotoxicity resulting in the development of encephalitis,
encephalopathy, seizures, and strokes. SARS-CoV-2 invasion on the brain stem is believed to be
responsible for the cardiorespiratory failures observed in Covid-19 patients. Apart from viral
invasion via hematogenous route, SARS-CoV-2 neural invasion via PNS nerve terminal, results in
viral replication and retrograde transportation to soma leading to invasion of the CNS including the
brain producing neurological manifestations of the disease either in the initial stages or during the
course of the disease and even for a long period post-infection in many cases. The ACE2 receptors
are expressed in the brain and glial cells and SARS-CoV-2 acts via neuronal as well as nonneuronal
pathways. But the exact cell types involved and how they can trigger inflammatory
pathways need further in-depth study for the development of targeted therapy.
